Those are the words Sophie O'Donnell uses to describe endometriosis.

The fitness trainer, ex-dancer, business owner and bride-to-be was told when she was 21 years old there was a 50 per cent chance she could never have children.

And that she should start trying for a baby as soon as possible.

"I hadn't even met my fiance Brent by then so that was a really hard thing to hear," Sophie said.

"And I think that has been the hardest mental battle as well.

"In the first few months of dating Brent I had to tell him that I might not be able to have children and that can be a deal breaker for some people."

Endometriosis is under-diagnosed and mostly unknown disorder where tissue that normally lines the uterus grows outside the uterus.

And the only way to diagnose it is to go under the knife.

"I think that is the most scary thing for people, especially if you are a young girl going through it," Sophie said.

"There is no ultrasound or blood test that can pick it up, you have to have a laparoscopy which is only keyhole surgery, but who wants to put their 14-year-old daughter through that if it might not be endo."

For Sophie she didn't know anything was wrong until she was about 16 years old.

"I was dancing and I had my period and would say 'oh my period pain is really bad' and everyone would just tell me to have a neurofen and get over it," she said.

"But there was only about five days out of the month where I wasn't having pain and that is when I realise that it wasn't a normal situation."

It wasn't until five years later when she found out it was endometriosis.

"I went on the pill for a few years because I thought that would control my period pain a bit better but it did nothing," Sophie said.

"I then went and saw a specialist and he said the only way for me to know was to have the surgery.

"I went and had my first laparoscopy when I was 21.

"The doctor told me I have stage 5 endometriosis which is the worst stage.

"There were pieces in there that were around a 20 cent piece and some cysts throughout and I think the most common misconception with endo is that it is only on your ovaries.

"Mine is actually all over my bowel.

"It is like a weed it starts in one place and feeds off that.

"I have had another surgery since then but they don't do anything other than help with fertility down the track.

"So I don't think I will have another one until we are nearly ready to try for kids."

The most common symptom of endometriosis is what feels like a really painful period and the now 23-year-old said everyone is different.

"Mine is very isolated pain near my bowel and my uterus," Sophie said.

"For some people who have stage 1 endo they have the laparoscopy and have it cleaned out and it never comes back but everyone is different.

"The severity is so different with everyone and the type is really different too.

"It is one of those things because there is no treatment and there isn't one type."

Everyday is different for Sophie. And managing her symptoms and listening to her body is something she continues to learn.

"Somedays you can wake up and can be sore just from not doing anything and then some days it is like a paper cut that is stinging but isn't too bad," she said.

"Some times I eat something that reacts with it or someone tells me something stressful and it flares up.

"You get really severe bloating but it gets to the point where I go up about two sizes in clothing when I get a flare up.

"It is like a burning and stabbing sensation.

"The two biggest things for me are food sensitivity and stress which cause me to have a flare up."

Working as a fitness trainer at Vice Fitness Albury with her fiance Brent "forced" her to be active.

"Some days you just want to not do anything but the thing for me what that I had to get up and move and that has been the best thing for me," she said.

"And after a lot of research I now only eat a plant-based diet, don't drink alcohol or eat gluten and try not to consume any inflammatory foods.

"It is just easier to process. It is just one less job for your body to be doing."

Sophie said she might "come across as being over the top" with her healthy lifestyle but it is about "preventative measures".

"I actually don't like talking about it. At the end of the day there is nothing anyone can do about it so I don't like to put people in that situation," she said.

"But in saying that people need to know what it is.

"Most people see me working out and in the gym and endo isn't something you can see so it is hard when you are having an off day not to show that pain.

"Brent is really understanding which I am so grateful for, he gets that some days that don't happen often, but I can't take classes so he just steps in.

"There are probably women who have it but aren't diagnosed and just think the horrendous pain is normal - it isn't."

Sophie has found support through sharing her story on her social media accounts and Facebook support groups.

"It is easier to share your story online I think," she said.

"I am in a support group on Facebook and the different stories you hear from women are just incredible.

"One woman responded to me when I said it was on my bowel and she said it also spread to underneath her lung.

"People just don't realise what endo is until they have to and I think the more awareness we raise for it the more people will be diagnosed and the bigger push there will be for a cure and treatment."

Although Sophie and Brent "aren't quite ready" to have children it is something they continue to talk about.

"We don't like to be negative - it is a when not an if for us.

"We are getting married soon so I think we will work on our business a bit after that and then maybe start trying.

"But if we can't at least I know I have given myself the best chance to have children through my lifestyle and what I put in my body.

"I am just focusing on my health and happiness at the moment."

Sophie hopes by sharing her story more women will speak about endometriosis and will prompt more doctors to try and find a treatment or cure.